Dyeing of synthetic fibers



nited. Sta s tfif0 3,353,900 DYEING F SYNTHETIC FIBERS Julian J. Hirshfield and Byron A. Sample, Jr., Decatur, Ala., assignors to Monsanto Company, St. Louis, Mo., a corporationof Delaware No-Drawing. Filed Feb. 11, 1966, fier. No. 538,115

14 Claims. (Cl. 8-55) ABSTRACT OF THE DISCLOSURE This invention relates to the dyeing of synthetic fibers. More particularly, the invention relates-to the use of furfural to assist the dyeing of synthetic fibers. This is a continuation-in-part application of application; Sem -"No;

304,619, filed Aug. 26, 1963, and application-Set. No;

304,620, filed Aug. 26, 1963, these applications are n abandoned. 3

Dyeing of fibers, especially the highly oriented synthetic 3,3533% Patented Nov. 21, T967 liter up to about the saturation point of the furfural v the aqueous dye bath.

' factured fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85%- by weight of an ester of a dihydric alcohol and a dicarboxylic acid or derivative thereof, for example terephthalic acid and dimethyl terephthalate), olefin fiber (a manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of at least 85% by weight of ethylene, propylene, or other olefin units), modacrylic fiber (a manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of less than 85% but at least by weight of acrylonitrile units), spandex fiber (a manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer composed of at least f 85% by Weightof a segmente'dpolyurethane), polyamide fiber-ta manufactured fiber in' which the fiber-forming substance is any'long-chain synthetic polyamide having recurri'ng'amide groups (-',CONH-) as an integral fibers, is a difiicult problem the textile industryis faced with. The qualities of synthetic fibers which make them advantageous, i.e. the hydrophobic nature of the fibers, their resistance to chemical agents, their limited swelling characteristic, and the smooth surfaces of these synthetic fibers, make them difficult to dye. More specifically, these i qualities make the penetration and retention of dyes very diificult. q

Dyeing of synthetic fibers at temperatures below the boiling point of thedyebath has generally proved unsuccessful, for example such a dyeing procedure usually 're-. sults in merely coloring the fiber with a light shade of. the dye and usually results in ring dyeing, i.e. a cross section of the fiber would indicate no dye penetration. In order to obtain good penetration and shading of the, dye on the fiber, dyeing procedures have incorporated high temperatures, i.e. temperatures above the boiling point of the dyebath, high pressures and agents to swell or open the fiber to permit the ingress of the dye into the fiber. The use of high temperatures and high pressures in dyeing procedures however increase considerably the cost of dyeing synthetic fibers. Also, certain dyes are not applicable with high temperature type dyeing procedures, i.e. the dyes tend to break down at these high tempera tures.

a novel method of dyeing synthetic fibers.

Another object of this invention is to provide a method of dyeing synthetic fibers at temperatures at and below the boiling point of the dyebath and which resultin good shading 'of the fiber and with good penetration of the dye on the fiber.

Yet another object of this invention is to provide a method of dyeing synthetic fibers with all classes of dyes which results in good dye penetration of the fiber and with good shading of the dye on the fiber.

Still another object of the invention is to provide synthetic fibers dyed by the process of this inventionwhich exhibit good dye penetration and good shading of the dye on the fiber.

These and other objects of the ihvention are accomplished by providing a process of dyeingsynthetic fibers which comprising contacting the fiber withan aqueous dyebath containing a dye and furfural, the furfural at a partfof the polymer chain), acrylic fiber (a manufactured fiber in which the fiber-forming substance is any longchainsynthetic polymercomposedof at least 85% by weight of acrylonitrile units) and acetate fiber (a manus factured fiber in which the fiber-forming substance is cellulose acetate; where not less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description'of the fiber). Blends of the above synthetic fibers are useful also withthe invention.

Dyes useful with the invention include disperse dyes, basic .-dyes, acid dyes,-vat -dyes,-,sulfur dyes, acid-premetallized dyes, neutral-premetallized .dyes, etc. It is to It is therefore an object of this invention to provide be understood, that certain .dyes are preferred with certain fibers, for example disperse dyes with polyester fiber. The dyes useful with this invention are present in an aqueous medium, hereinafter referred to as an aqueous dyebath. The aqueous" dyebath may contain constituents other than the dye and furfural,1such as an anionic detergent, etc.; however such constituents without the furfural cannot achieve the shading and penetrations of the dye on the fibers as taught by the process of this invention.

The aqueous dyebath contains a small percentage of the dye to effect the coloring of the fabric. The shade of the color on the fabric can be controlled by the concentration of the furfural in the dyebath. For example, furfural within the concentration range of from about 5 grams per liter up to about the saturation point of the furfural in the dyebath produces good shades of colors on the fibers and good penetration of the dyes on the fibers. Concentrations of furfural whichexceed the saturation point of the furfural in the dyebath-however produce undesirable affects on the fiber, for example dyeing concentration within the range of from about 5 grams per with overly'saturated concentrations of furfural in the dyebath produce blotchs or streaks on 'the fiber. It is therefore preferred that the concentration of the furfural never exceed its saturation point in the aqueous dyebath. Where high concentrations of furfural are desired in the dyebath, concentrations of metallic sulfates, e.g.

sodiumsulfate, magnesium sulfate, zinc sulfate, aluminum sulfate and potassium sulfate, up to about fifteen grams per liter in the dyebath are beneficial to solubilize the furfural. For example, 150 grams of furfural can be solubilized in one liter of an aqueous dyebath by mixing about 12 grams of sodium sulfate with the dyebath. Concentrations of furfural in the aqueous dyebath within the range of from about 101 grams per liter up to about grams per liter are preferred. a

The temperature of the dyebath should be within the range of from about 100 F. up to about the boiling point of the aqueous dyebath. Temperatures down to about 75 F. are useful, however at such low temperatures the contact time of-the fabric in the dyebath would be increased, for example in some cases it couldrequire up to about 12 hours to sufliciently dye the fabric. Temperatures above the boiling point of the aqueous dyebath are also useful, however such temperatures are not necessary to produce good dyeing of the fibers.

At the above temperatures of the dyebath, i.e. from about 100 F. up to about the boiling point of the aqueous dyebath, the contact time of the fiber in the dyebath can be within the range of a few seconds up to an unlimited amount of time. The shorter period of contact time is preferred at the higher temperatures of the dyebath. For good shades of dye colors and for good dye penetration, it is preferred that the period of contact time be within the range of from about seconds up to about 60 minutes.

The following examples are presented to illustrate the invention. Such examples are not to be considered as a limitation of the invention but are presented as more working examples of the invention. Percents where used are based on weight unless otherwise specified.

EXAMPLE I A swatch of polyester fabric composed of fibers of 100% polyethylene terephthalate is immersed for 30 minutes in a dye bath (liquor to goods ratio 30:1) at 120 F. containing 0.5 gram per liter of Acetamine Scarlet B, a tradename of E. I. du Pont de Nernours and Co., Inc., Wilmington, Del. (C.I. Name Disperse Red 1), Cl No. 11110) 0.5% Igepon T-51 (a sodium N-methyl-N-oleoyltaurate, marketed by General Aniline Film Corp.) and grams per liter of furfural. The swatch is removed from the dye bat-h and thoroughly rinsed in both warm and cold water. Analysis of the swatch shows that it is dyed pink. A similar swatch is treated as herein described except the furfural is absent; analysis of this swatch shows that it is not dyed.

EXAMPLE II A swatch of polyamide fabric composed of fibers of 100% of a polymer obtained from the polymerization of hexamethylene diamine and adipic acid is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 0.5 gram per liter of Acetamine Scarlet B (Cl. Name Disperse Red 1), 0.5% of Igepon T-5l and 50 grams per liter of furfural. The swatch is thereafter removed and thoroughly rinsed in warm and cold water. Analysis of the swatch shows it is dyed a deep shade of red. An identical swatch of fabric is processed as described above except that the furfural is absent; analysis of this swatch shows that it is colored a medium pink.

EXAMPLE III A swatch of acrylic fabric composed of fibers of a terpolymer of 88% acrylonitrile, 6% methylvinylpyridine and 6% vinyl acetate is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 0.5 gram per liter of Acetamine Scarlet B (Cl. Name Diseperse Red 1), 0.5% of Igepon T-51 and 50 grams per liter of furfural. The swatch is removed from the dyebath and rinsed in both warm and cold water, Analysis of the swatch shows it is dyed a dee shade of red. An identical acrylic swatch is treated as described herein except the furfural is absent; analysis of this swatch shows that it is not dyed.

EXAMPLE IV An acrylic swatch of fabric composed of fibers of blend of two copolymers being 88% of a copolymer of 94% acrylonitrile and 6% vinyl acetate and 12% of a copolymer of 50% acrylonitrile and 50% methyl vinylpyridine, is immersed for 30 minutes in an aqueous dye- A polyester swatch of fabric composed of fibers of 100% polyethylene terephthalate is immersed for minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 160 F. containing 0.5 gram per liter of Acetamine Scarlet B (C.I. Name Disperse Red 1),

0.5% of Igepon T-51 and 10 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warn and cold water. Analysis of the swatch shows that it is dyed a pink color. An identical polyester swatch is treated as described herein except the furfural is absent; analysis of this swatch shows that it is slightly stained.

EXAMPLE VI A polyamide swatch composed of fibers of 100% Of poly (hexamethylene adipamide) is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio 30:1) at 160 F. containing 0.5 gram per liter of Acetamine Scarlet B (Cl. Name Disperse Red 1), 0.5% of Igepon T-51 and 10 grams per liter of furfural. Thereafter the swatch is removed and thoroughly rinse-d in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of red. An identical polyamide swatch is treated as described herein except the furfural is absent; analysis of this swatch shows that it is dyed a very light shade of red.

EXAMPLE VII An acrylic swatch of fabric composed of fibers of 99% polyacrylonitrile and 1% polyvinylpyrrolidone is immersed for '60 minutes in an aqueous dyebath (liquor to goods ratio of 30:1) at 160 F. containing 0.5 gram per liter of Acetamine Scarlet B (Cl. Name Disperse Red 1), 0.5% of Igepon T51 and 50 grams per liter of furfural. The swatch is removed and rinsed thoroughly in warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of red. An identical acrylic swatch is treated as described herein except the furfural is absent; this swatch shows that it is dyed a very light shade of red.

EXAMPLE VIII An acrylic swatch of fabric composed of fibers of a blend of two copolymers of which 88% is a copolymer being 94% acrylonitrile and 6% vinyl acetate and 12% is the second copolymer being 50% acrylonitrile and 50% methyl vinylpyridine, is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 5%, based on the weight of the fabric, of Alizarine Direct Blue ARA, a tradename of General Aniline and Film Corp., Dyestuff & Chemical Div., New York, N.Y., (Cl. Name Acid Blue 41, Cl. No. 62130), 5% of formic acid, based on theweight of the fabric, and 10 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical acrylic swatch is treated as described herein except the furfural is absent; this swatch shows a light shade of blue.

EXAMPLE IX A polyamide swatch of fabric composed of fibers of poly (hexamethylene adiparnide) is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at F. containing 5% of Alizarine Direct Blue ARA (Cl. Name Acid Blue 41), based upon the weight of the fabric, of formic acid, based upon the weight of the fabric, and 50 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical polyamide swatch is treated as described herein except the furfural is absent; this swatch shows it is dyed a light shade of blue.

EXAMPLE X An acrylic swatch of fabric composed of fibers of two copolymers of which 88% is a copolymer of 94% acrylonitrile and 6% vinyl acetate and 12% is a copolymer of 50% acrylonitrile and 50% methyl vinylpyridine, is immersed for 60 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 160 F. containing 5% of Alizarine Direct Blue ARA (C.I. Name Acid Blue 41), based upon the weight of the fabric, 5% of formic acid, based upon the weight of the fabric, and 10 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a dee shade of blue. An identical acrylic swatch is treated as described herein except the furfural is absent; analysis of this swatch shows it is dyed a light shade of blue.

EXAMPLE XI Au acrylic swatch of fabric composed of fibers of a blend of two copolymers of which 88% is a copolymer of 94% acrylonitrile and 6% vinyl acetate and 12% is copolymer being 50% acrylonitrile and 50% methylvinylpyridine is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 5% (based on fabric weight) of Cibalan Yellow GRL, a tradename of Ciba Chemical and Dye Company, Tap Div., Fair Lawn, NJ. (C.I. Name Acid Yellow 116), 5% (based on fabric weight) of formic acid and 10 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of yellow. An identical acrylic swatch is treated as de scribed herein except the furfural is absent; this swatch shows that it is dyed a light shade of yellow.

EXAMPLE XII A polyamide swatch of fabric composed of fibers of 100% poly (hexamethylene adipamide) is immersed for 30 minutes in aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 5% (based on fabric weight) of Cibalan Yellow GRL (C.I. Name Acid Yellow 116), 3% (based on fabric weight) of formic acid and 10 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of yellow. An identical polyamide swatch is treated as described herein except the furfural is absent; this swatch shows it is dyed a light shade of yellow.

EXAMPLE XIII An acrylic swatch of fabric composed of fibers being two copolymers of which 88% is a copolymer of 94% acrylonitrile and 6% vinyl acetate and 12% is a copolymer of 50% acrylonitrile and 50% methylvinylpyridine, is immersed for 30 minutes in an aqueous dyebath (liquor to goods ratio being 30:1) at 120 F. containing 5% (based on fabric weight) of Algosol Blue IBC, a tradename of General Aniline and Film Corp., Dyestuff & Chemical Div., New York, NY. (C.I. Name Solubilized Vat Blue 6, Cl. No. 69826), 3% (based on fabric weight) of sodium sulfoxylate formaldehyde, 2% (based on fabric weight) of concentrated sulfuric acid and 50 grams per liter of furfural. The swatch is removed from the dyebath and immersed for 30 minutes in a second bath at 160 F. containing 3% (based on fabric weight) of sodium nitrite and 3% (based on fabric weight) of concentrated sulfuric acid. Thereafter, the swatch is removed and is thoroughly rinsed in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical acrylic swatch is treated as described herein except the furfural is absent; this swatch shows it is dyed a light shade of blue.

EXAMPLE XIV A polyamide swatch of fabric composed of fibers of poly (hexarnethylene adipamide) is immersed for 30 minutes in an aqueous dyebath at F. containing 5% (based on fabric weight) of Algosol Blue IBC (C.I. Name Solubilized Vat Blue 6), 3% (based on fabric weight) of sodium sulfoxylate formaldehyde, 2% (based on fabric weight) of concentrated sulfuric acid, and 50 grams per liter of furfural. The swatch is removed from the dyebath and is immersed for 30 minutes in a second aqueous bath at F. containing 3% (based on fabric weight) of sodium nitrite and 3% (based on fabric weight) of concentrated sulfuric acid. Thereafter, the swatch is removed and is thoroughly rinsed in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical polyamide swatch is treated as described herein except the furfural is absent; analysis of this swatch shows that it is dyed a light shade of blue.

EXAMPLE XV An acrylic swatch of fabric composed of fibers being 99% polyacrylonitrile and 1% polyvinylpyrrolidone is immersed for 60 minutes in an aqueous dyebath at 120 F. containing 5% (based on fabric weight) of Algosol Blue IBC (C.I. Name Solubilized Vat Blue 6), 3% (based on fabric weight) of sodium sulfoxylate formaldehyde, 2% (based on fabric weight) of concentrated sulfuric acid and 10 grams per liter of furfural. The liquor to goods ratio is 30:1. The swatch is removed from the dyebath and immersed for 30 minutes in a second aqueous bath at 160 F. containing 3% (based on fabric weight) of sodium nitrite and 3% (based on fabric weight) of concentrated sulfuric acid. Thereafter, the swatch is removed and thoroughly rinsed in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical acrylic sample is treated as described herein except the furfural is absent; analysis of this swatch shows that it is dyed a light shade of blue.

EXAMPLE XVI A polyamide swatch of fabric composed of fibers of 100% poly (hexamethylene adipamide) is immersed for 30 minutes in an aqueous dyebath at 160 F. containing 5% (based on fabric weight) of Algosol Blue IBC (Cl. Name Solubilized Vat Blue 6), 3% (based on fabric weight) of sodium sulfoxylate formaldehyde, 2% (based on fabric weight) of concentrated sulfuric acid and 10 grams per liter of furfural. The liquor to goods ratio is 30:1. The swatch is then removed from the dyebath and is immersed for 30 minutes in a second bath (liquor to goods ratio being 30: 1) at 160 F. containing 3% (based on fabric weight) of sodium nitrite and 3% (based on fabric weight) of concentrated sulfuric acid. Thereafter, the swatch is removed from the bath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue. An identical polyamide swatch is treated as described herein except the furfural is absent; analysis of this swatch shows it is dyed a light shade of blue.

EXAMPLE XVII Three acrylic samples each weighing 5 grams and composed of fibers being 94% acrylonitrile and 6% vinyl acetate are immersed in separate but identical boiling, aqueous dyebaths, each dyebath having a volume of 200 cc. and containing 5 grams per liter Acetamine Scarlet B (C.I. Name Disperse Red 1) and 90 grams per liter of furfural and are maintained in the dyebaths for 10 seconds, 30 seconds and 60 seconds respectively. The samples are removed from their respective dyebaths; analyses show that all three are dyed a deep shade of red with intensity increasing with the increase in immersion time. Thereafter, the samples are scoured in an aqueous solution containing 1% (based on fiber weight) of Igepal CO-63O (a wetting agent defined as an alkylphenoxypoly (ethyleneoxy)-ethanol, marketed by General Aniline and Film Corp.) and 0.5% of trisodium phosphate for 30 minutes at 160 F. Thereafter the samples are removed. Analyses of the samples show that they retain their deep shade of red coloration, they have good wet fastness, the 30 seconds and 60 seconds immersion time samples have full fiber cross-scetion penetration of the dye and the 10 seconds immersion time sample has about 60% fiber cross-section penetration.

EXAMPLE XVIII A 2 gram acrylic sample containing fibers being 94% acrylonitrile and 6% methylacrylate is immersed for 60 seconds in 200 mls. of a boiling aqueous solution containing grams per liter of Acetamine Scarlet B (CI. Name Disperse Red 1) and 90 grams per liter of turfural. The samples are scoured as described in Example XVII. Analysis of the sample shows that it is dyed a deep shade of red, the sample has excellent wet fastness, and a crosssection analysis of the fiber shows that it is fully penetrated with the dye.

EXAMPLE XIX Three polyamide samples each weighing 2.5 grams and each composed of fibers of poly (hexamethylene adipa-mi-de) are immersed for 10 seconds, 30 seconds, and 60 seconds, respectively, in 200 cc. of boiling aqueous dyebaths each containing 5 grams per liter of A-macel Yellow G, a tradename of American Aniline Products, Inc, Paterson, NJ. (C.I. Name Disperse Yellow 3, Cl. No. 11855), and 90 grams per liter of furfural. The samples are removed from their dyebaths and it is observed that they are dyed a deep shade of yellow. The samples are scoured for 30 minutes in an aqueous solution at 160 F. containing 1% (based on fiber weight) of Igepal CO-630, and 0.5% of trisodium phosphate. The samples are removed from the scour. Analyses of the samples show that they are all dyed a deep shade of yellow and cross-section analyses of the fibers within each sample shows a dye penetration of from 50% to 75%.

Three identical polyamide samples as described above are treated as described above except the dyebaths have 1 gram per liter of Igepon T-51 substituted for the furfural. Analyses of these samples show that they are merely dyed on the surface without any substantial dye penetration on the fiber.

EXAMPLE XX Three acrylic samples each weighing 5 grams and each composed of fibers being 75% of a copolymer of 94% acrylonitrile and 6% vinyl acetate, 12% of a copolymer being 50% acrylonitrile and 50% methyl vinylpyridine and.13% of polyvinylchloride are immersed for 10 seconds, 30 seconds and 60 seconds, respectively, in boiling aqueous dyebaths of 200 cc. containing 5 grams per liter of Xylene East Red 6B, a tradename of Sandoz, Inc., New York, N.Y. (Cl. Name Acid Violet 14, Cl. No. 17080), 2 grams per liter of acetic acid and 90 grams per liter of furfural. After removal from the dyebaths, analyses of the samples show that all samples are dyed a deep shade of red and cross-sectional analyses of the fibers show a deep penetration of the dye on the fiber.

EXAMPLE XXI A 10 gram polyester swatch composed of fibers being polyethylene terephthalate are immersed for 5 minutes in 200 cc. of a boiling aqueous dyebath containing 1 gram per liter of Celliton-Fast Yellow 4 RL, a tradename of General Aniline and Film Corp, Dyestufi and Chemi- 8 cal Div., New York, NY. (C1; Disperse Yellow 23, Cl. No. 26070), 1 gram per liter of Acetamine Scarlet B (CI. Name Disperse Red 1) and 50 grams per liter of furfural. Cross-section analysis of the polyester fiber shows that it is fully penetrated with the dye.

EXAMPLE XXII A polyester swatch described in Example XXI is treated as described in Example XXI except the dyebath contains grams per liter of furfural and the swatch is immersed for 20 minutes in the boiling aqueous dyebath. A cross-section analyses of the fiber shows that it is fully penetrated with the dye.

EXAMPLE XXIII EXAMPLE XXIV An acrylic swatch of fabric composed of fibers being 88% acrylonitrile, 6% vinyl acetate and 6% methylvinylpyridine is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Fastusol Blue LBRR, a tradename of General Aniline and Film Corp, Dyestufi and Chemical Div., New York, NY. (Cl. Name Direct Blue 71), CI. No. 34140, 10% sodium chloride, 0.5% soda ash and 40 grams per liter of furfural. The swatch is removed from the dyebath and rinsed in warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue.

An identical acrylic swatch is treated as described above except the furfural is absent; analysis of this swatch shows that it is dyed a light shade of blue.

EXAMPLE XXV An acrylic swatch of fabric composed of fibers being 88% acrylonitrile, 6% vinyl acetate and 6% methylvinylpyridine is immersed for 20 minutes in a boiling aqueous bath (liquor to goods ratio being 40:1) at F. containing 1 gram per liter of Ciba Micro Blue 2B Powder, a tradename of Ciba Chemical and Dye Company, Tap Div., Fair Lawn, NJ. (Cl. Name Vat Blue 5), 0.1. No; 73065, 3% hydrosulfide, 3% soda ash and 40 grams per liter of furfural. The swatch is removed from the dyebath and thoroughly rinsed in both warm and cold water. Analysis of the swatch shows it is dyed a light greenishblue shade.

An identical acrylic swatch is treated as described above except the furfural is absent; analysis of this swatch indicates that it is a faintly stained with the color.

EXAMPLE XXVI An acrylic swatch of fabric composed of fibers being 99% poly acrylonitrile and 1% polyvinylpyrrolidone is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Celliton Fast Blue FERN, a tradename of General Aniline and Film Corp., Dyestuif and Chemical Div., New York, N.Y. (Cl. Name Disperse Blue 3), Cl. No. 61505, 0.5% of Igepon T-51 and 40 grams per liter of furfural. The swatch is removed from the dyebath and thoroughly rinsed in both cold and warm water. Analysis of the swatch shows that it is dyed a heavy shade of blue.

An identical acrylic swatch is treated as described above except the furfural is absent; analysis of this swatch shows it is dyed a medium shade of blue.

9 EXAMPLE XXVII An acrylic swatch of fabric composed of fibers being 99% acrylonitrile and 1% polyvinylpyrrolidone is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Alizarine Direct Blue ARA (C.I. Name Acid Blue 41), formic acid and 40 grams per liter of furfural. The swatch is removed from the dyebath and rinsed in both warm and cold water. Analysis of the swatch shows it is dyed a deep shade of blue.

An identical acrylic swatch is treated as described above except the furfural is absent; analysis of this swatch shows that it is dyed a lighter shade of blue.

EXAMPLE XXVIII A polyamide swatch composed of fibers being poly (hexamethylene adipamide) is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Fastusol Blue LBRRA (C.I. Name Direct Blue 71), sodium chloride, 0.5% soda ash and 40 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch indicated that it is dyed a deep shade of dark blue.

An identical polyamide swatch is treated as described above except that furfural is absent. Analysis of this swatch indicates that it is dyed a much lighter shade of blue.

EXAMPLE XXIX A polyamide swatch of fabric composed of fibers being poly(hexamethylene adipamide) is immersed for 20 minutes in an aqueous dyebath (liquor to goods ratio being 40:1) at 190 F. containing 1 gram per liter of Ciba Micro sulfide 2B Powder (C.I. Name Vat Blue 5), 3% of hydrosulfide, 3% of soda ash and 40 grams per liter of furfural. The swatch is removed from the dyebath and thoroughly rinsed in both warm and cold water. Analysis of the swatch indicates that it is dyed a deep shade of blue.

EXAMPLE XXX A modacrylic swatch of fabric composed of fibers being 43% acrylonitrile and 57% polyvinylchloride is immersed for 20 minutes in a boiling aqueous dyebath (liquor for goods ratio being 40: 1) containing 1 gram per liter of Celliton Fast Blue FFRN (C.I. Name Disperse Blue 3), 0.5% of Igepon T-51, and 40 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch shows that it is dyed a deep shade of blue.

An identical modacrylic swatch is treated as described above except the furfural is absent. Analysis of this swatch shows that it is dyed a lighter shade of blue.

EXAMPLE XXXI A 1 gram spandex sample composed of spandex fibers is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Celliton Blue FFRN (C.I. Name Disperse Blue 3), 0.5% of Igepon T-51 and 40 grams per liter of furfural. The sample is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the sample indicates that it is dyed a deep shade of blue.

An identical spandex sample is treated as described above except the furfural is absent. Analysis of this sample indicates that it is dyed a much lighter shade of blue.

EXAMPLE XXXII A 1 gram spandex sample of spandex fibers is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Alizarine Direct Blue ARA (C.I. Name Acid Blue 41), 5% of formic acid and 40 grams per liter of furfural. The sample is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the sample indicates that it is dyed a deep shade of blue.

10 An identical spandex sample is treated as described above except that the furfural is absent. Analysis of this sample indicates that it is dyed a much lighter shade of blue.

EXAMPLE XXXIII A 1 gram spandex sample of spandex fibers is immersed for 20 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Fastusol Blue LBRRA (C.I. Name Direct Blue 71), 10% of sodium chloride, 0.5% of soda ash and 40 grams per liter of furfural. The sample is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the sample indicates that it is dyed a deep shade of blue.

An identical spandex sample is treated as described above except the furfural is absent. Analysis of this sample indicates that it is dyed a very light shade of blue.

EXAMPLE XXXIV A 1 gram spandex sample of spandex fibers is immersed for 20 minutes in an aqueous dyebath (liquor to goods ratio being 40:1) at 190 F. containing 1 gram per liter of Ciba Micro Blue 2B Powder (C.I. Name Vat Blue 5), 3% of hydrosulfide, 3% of soda ash and 40 grams per liter of furfural. The sample is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the sample indicates that it is dyed a deep shade of blue.

An identical spandex sample is treated as described above except the furfural is absent. Analysis of this sample indicates that it is dyed a very light shade of blue.

EXAMPLE XXXV A polyester swatch of fabric composed of fibers being 100% polyethylene terephthalate is immersed 'for 5 minutes in a boiling aqueous dyebath (liquor to goods ratio being 40:1) containing 1 gram per liter of Celliton Fast Yell-ow 4 RL (C.I. Name Disperse Yellow 23) and 50 grams per liter of furfural. The swatch is removed from the dyebath and rinsed thoroughly in both warm and cold water. Analysis of the swatch indicates that it is dyed a deep shade of orange-yellow.

What is claimed is:

1. A process of dyeing synthetic fibers which comprises contacting the fiber with an aqueous dyebath at a temperature within the range of from about 100 F. up to about the boiling point of the dyebath, said dyebath consisting essentially of a dye and furfural, the furfural at a concentration within the range of from about 5 grams per liter up to about the saturation point of the furfural in the aqueous dyebath.

2. The process of claim 1 wherein the synthetic fiber is an acrylic fiber.

3. The process of claim 1 wherein the synthetic fiber is a polyamide fiber.

4. The process of claim 1 wherein the synthetic fiber is a polyester fiber.

5. The process of claim 1 wherein the synthetic fiber is a spandex fiber.

6. The process of claim 1 wherein the concentration of the furfural in the dyebath is within the range of from about 10 grams per liter up to about grams per liter.

7. A process of dyeing synthetic fibers which comprises immersing the fiber in an aqueous dyebath at a temperature within the range of from about F. up to about the boiling point of the dyebath for a period of time of from about 5 seconds up to about 60 minutes, said aqueous dyebath consisting essentially of a dye and furfural, the furfural at concentration within the range of from about 5 grams per liter up to about the saturation point of the furfural in the aqueous dyebath.

8. The process of claim 7 wherein the synthetic fiber is an acrylic fiber.

9. The process of claim 7 wherein the fiber is a polyamide fiber.

10. The process of claim 7 wherein the fiber is a poly- References Cited ester fibera UNITED STATES PATENTS 11. The process of claim 7 whereln the fiber 1s an olefin 1 760 076 5/1930 Miner 8 93 X fiber. 1

12. The process of claim 7 wherein the fiber is a 5 1989802 2/1935 Hgster et a1 894'24 X Spandex fiben 2,174,005 9/1939 Miller 893 X 13. The process of claim 7 wherein the temperature of 2700589 V1955 Innamne 855 the dyebath is at the boiling point of the aqueous dyebath. 14. The process of claim 7 wherein the concentration NORMAN TORCHIN Prlmary Exammel' of the furfural in the'dyebath is within the range of from 10 HERBERT, Assistant Examinerabout 10 grams per liter up to about 90 grams per liter. 

1. A PROCESS OF DYEING SYNTHETIC FIBERS WHICH COMPRISES CONTACTING THE FIBER WITH AN AQUEOUS DYEBATH AT A TEMPERATURE WITHIN THE RANGE OF FROM ABOUT 100*F. UP TO ABOUT THE BOILING POINT OF THE DYEBATH, SAID DYEBATH CONSISTING ESSENTIALLY OF A DYE AND FURFURAL, THE FURFURAL AT A CONCENTRATION WITHIN THE RANGE OF FROM ABOUT 5 GRAMS PER LITER UP TO ABOUT THE SATURATION POINT OF THE FURFURAL IN THE AQUEOUS DYEBATH. 